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Broken exhaust header bolt removal questions.

5898 Views 38 Replies 8 Participants Last post by  TLJimmy
Berfore I break out the drill or dremel I'd like to have a good go at welding a nut on the broken bolt, although I don't know if the fact it snapped off short precludes this method.

Auto part Automotive exterior Bumper
Auto part

I had a go using a Mig welder, and a nut with a thread diameter the same as the broken bolt. I think this nut may've been too small, as it filled up nicely, but only managed to get a tack down onto the bolt, as you can see in the second photo. My next thought is to use a much bigger nut, enabling the wire or rod to get right down in there before it starts arcing:O.

Auto part Wheel

If I do this, will the exposed area of engine between the bolt and the nut cause any issues? ie, should I cover it with a smaller diameter washer first, placing the nut over this to weld?

Lastly, do I need to Mig weld it? I have an arc welder at home - using the mig means I have to transport the engine across town.

Any help will be much appreciated.
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I use a stick and a big nut works real well

just let it cool before trying to unwind it.

give it a couple of taps with a hammer and work it back and forth as you ease it out.

if it tears off then just weld another on.
Fill the nut up once you have covered the end of the thread

the extra heat frees the thread
Cool it with WD40 and use it after rides you won't have this problem again. :thumbup
It's an engine out of a crashed bike that has been sitting for two years....

I'll either reassemble with copper-slip, or replace with a stud and a copper nut.

That bitch is STUCK. Had 3 trys - first time not enough heat., second time got a nice long extension on the bolt, but welding from the middle, the slag spitting meant I didnt get a good weld on the nut. Hacksawed the 'extension' so its length was 1/3 nut width and got a good weld. Wouldn't budge, and sheared off my bolt again. Third time, with a bit more heat, and Ill try it a bit later. I've got a feeling it may be time for step 2....:(

Nut sheared again - probably my welding:coocoo. Had another plan though - I built up a nice long shaft again (I'mgood at that at least:lol) and filed two parallel flats in it, then actualy got it to move a teeny bit, until it started to 'round'. Crescent is too imprecise, and my vice grips are ancient and worn. Tomorrow I'll get some shiny new 'grips and have another go:O
I just undid my own . After 13 years of ownership
1st time ever undoing them was a breeze .
Sounds like it's seen plenty of heat. If you reckon it moved a little keep applying the penetrating fluid until you pick up your new grips. In the past I've successfully used a micro torch to apply 'precision' heat to either a bolt or stud. I also used pipe freeze in conjunction with precision heat to remove a sheared bolt from a fork leg .... Not sure what actually did the trick maybe a combination of everything but the offending object came out sweet as you like.
If you install with copperslip they come out easy. I took my TLS exhaust off to polish, when I first got it it, and the bolts were really hard to move - if I'd left it much longer I'da had the same trouble as now. I bolted it back up with copperslip, neglected it and rode in all weather for the next 8 years (55 000km's). Took them off recently, and they slid out no trouble.
Sounds like it's seen plenty of heat. If you reckon it moved a little keep applying the penetrating fluid until you pick up your new grips. In the past I've successfully used a micro torch to apply 'precision' heat to either a bolt or stud. I also used pipe freeze in conjunction with precision heat to remove a sheared bolt from a fork leg .... Not sure what actually did the trick maybe a combination of everything but the offending object came out sweet as you like.
I'm down with that - throw the 'kitchen sink' at it. I might gently warm the area around it tomorrow, then apply some 'cold' to the bolt itself (butane for filling the soldering iron should work, if I can keep it off the cases), and see what happens...
Kenny-TLS Screw the WD-40 after every ride. Remove the steel bolts and replace them with stainless studs. Then use doubled brass nuts. They will never stick on the stainless, and if they do it will never harm the stainless. If necessary, you can use a nut splitter and replace the nuts. It's a permanent foolproof solution to the problem, guaranteeing peace of mind without any ritual after every ride.
keep after it with the welder jimmy. you'll get there

just be gentle with the nut as you lever on it
Thanks Sam. Main issue is I don't have a dremel, but I do have a welder:)
If the engine is already removed, you do have one more reliable option. For a reasonable fee a good machine shop will EDM the old bolt out, without any damage to the head. That is the real "official" standard technique that is employed after a reverse-screw drill or extractor fail or are not trusted. It's pretty foolproof with a competent operator, and the price is usually reasonable. No high heat involved.

Stu and others get this welding trick to work, but the aluminum will conduct the welding heat away pretty fast, so you need a LOT of current. And melting steel inside of aluminum threads definitely can distort the aluminum threads. So dialing in the correct current could be critical.

The EDM method is much safer and more reliable. Find a big machine shop with EDM equipment. It slowly erodes the steel regardless of its hardness, until there's just a spiral of thread left, which comes out easily. I really recommend EDM before it gets too screwed up with welding attempts. It's the more "correct" fix. Of course, anything that works is welcome...but that's my advice.
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The EDM option is the high-precision version of Sam's technique. It won't wander off the hard steel like a drill can, and it won't damage any threads in the head.
This'll be my last weld attempt. I tried on a lower setting, but had to increase it quite a bit. I got good welds and penetration, but she's also getting pretty damn hot. After filing flats on either side I got the bolt out about 1/4 turn with a crescent, but it started rounding so I stopped, cleaned it up with the file, and soaked it WD40. It's bloody tempting to have another go with the crescent...but I will go and buy some thin-nosed mole-grips, with fine teeth on the jaws - I think they'll do the trick.

If I get desperate and then the worst happens, I'll be hunting out an EDM to remove the snapped off drill-bitt in the head:laugh

I have succesfully drilled out a snapped bolt in an alloy head before, but it was nerve wracking. I have also snapped a drill-bitt, drilling the bolt out of a TLS clipon.

If you decide to go at it with an extractor, don't use the EZ out high tempered steel ones. They will break. Either get a really good set of left handed drills and just slowly step up the size or try this extractor:

I've been amazed at what it has gotten out! I don't know if you guys have a penetrating fluid called PB blaster over there but it is pretty amazing stuff too.

I just got a bolt out last night with a left handed drill and a center punch.

I used to do this for a living.

trust me a screw extractor of any description is not going to move it and neither is any penetrant you could imagine.


if all else fails the easy way is to grind the side out of the boss and puch the stud out sideways.

its a simple task then to tig the damage back up and redrill the hole into the fresh ali and rethread it.

a welding shop or a boat repair place can ali weld it .

spark discharge units are pretty thin on the ground in the southern hemisphere.
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Bummer. EDM equipment is pretty common stuff here, perhaps because of the now-declining aircraft & aerospace industry. It was pretty common in the northern Midwest too. Any broken bolts, I'd just routinely let someone else fix for a twenty dollar bill, but it might be more now.

If you do break a long hard extractor off inside the shaft, don't freak out; you can crack it up further or again EDM doesn't care how hard it is, it erodes thru hard steel just fine.

But reverse-screw drills are the standard first attack, and work surprisingly often. Just start with making a flat surface and center-punch the exact center, and don't let the drill drift around. As you change to larger and larger reverse drill bits, sometime before you're into the threads the whole thing often comes out. There's another art in choosing the right size drill step first you increment slowly and feed really slowly with lots of oil. Then you may want to go to a larger size and higher speed so that the drill suddenly seizes onto the bolt with a lurch and unscrews it! Of course, again there's the risk of breaking off a hard drill bit but you can usually get it out.

You can try calling around and finding out who has EDM equipment. I've even considered making my own.
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